Carrier firmware

garyHal

Senior Member
Jun 23, 2006
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I currently have the US s20Ultra unlocked model on ATT (don't foresee changing carriers). Currently I am missing features like VoLTE and VVM. What other features would I be missing if I stay on the unlocked firmware? Can I flash the ATT firmware to get those missing features? Can I flash back to unlock?

Thank you
 

varcor

Senior Member
Jul 15, 2017
335
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San Diego
Open your dialer, enter *#1234#, press the Dial Icon. You'll see CSC: G98??, the next 3 letters will be your device's CSC Code. Your Service Provider's CSC is "ATT" which is different than the CSC in your device. Whether or not you can change the CSC depends on your device's CSC. Device firmware is always configured for the specific, original CSC or Multi CSC's.

This post may be the best workaround.
https://forum.xda-developers.com/showpost.php?p=82444733&postcount=8
 
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garyHal

Senior Member
Jun 23, 2006
355
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Open your dialer, enter *#1234#, press the Dial Icon. You'll see CSC: G98??, the next 3 letters will be your device's CSC Code. Your Service Provider's CSC is "ATT" which is different than the CSC in your device. Whether or not you can change the CSC depends on your device's CSC. Device firmware is always configured for the specific, original CSC or Multi CSC's.

This post may be the best workaround.
https://forum.xda-developers.com/showpost.php?p=82444733&postcount=8
My CSC: G988U1OYM1ATE4
 

varcor

Senior Member
Jul 15, 2017
335
86
28
San Diego
My CSC: G988U1OYM1ATE4
Your device has Multiple CSC's which are included in OYM so you should be able to change your CSC to ATT, which is the CSC for AT&T.

Go to "Settings" then "About phone". Write down your IMEI Number. Open dialer and enter *#272*IMEInumber# (In the thread replace IMEInumber with your actual IMEI Number). Press the Dial Icon, you should see a screen with the list of available CSC codes for your device. Select ATT and tap the Install option.

Be aware your firmware isn't AT&T, it's unbranded so even if you change the CSC, full call functionality may not be available. You can obtain AT&T's firmware at SamMobile.

https://www.sammobile.com/samsung/galaxy-s20-ultra/firmware/SM-G988U1/ATT/
 
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garyHal

Senior Member
Jun 23, 2006
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Your device has Multiple CSC's which are included in OYM so you should be able to change your CSC to ATT, which is the CSC for AT&T.

Go to "Settings" then "About phone". Write down your IMEI Number. Open dialer and enter *#272*IMEInumber# (In the thread replace IMEInumber with your actual IMEI Number). Press the Dial Icon, you should see a screen with the list of available CSC codes for your device. Select ATT and tap the Install option.

Be aware your firmware isn't AT&T, it's unbranded so even if you change the CSC, full call functionality may not be available. You can obtain AT&T's firmware at SamMobile.

https://www.sammobile.com/samsung/galaxy-s20-ultra/firmware/SM-G988U1/ATT/
Varcor, thank you so much for all the directions.

As it stands right now, it is already on ATT. Once I flash over to the ATT firmware, would I be able to flash back to an unbranded one in the future, for whatever reason? Additionally, do I have to stay on the ATT firmware to retain those features? Or could just having my phone communicate with ATT at least once with my "branded" phone and then flash back retain those features?
 

varcor

Senior Member
Jul 15, 2017
335
86
28
San Diego
Varcor, thank you so much for all the directions.

As it stands right now, it is already on ATT. Once I flash over to the ATT firmware, would I be able to flash back to an unbranded one in the future, for whatever reason? Additionally, do I have to stay on the ATT firmware to retain those features? Or could just having my phone communicate with ATT at least once with my "branded" phone and then flash back retain those features?
You're most welcome. Yes, flashing back to unbranded won't be a problem. I don't think you will be able to retain the features if you go back to the unbranded firmware, it's not configured to allow full call feature functionality. Also, after flashing to the AT&T firmware you may need to contact their CSR for external programing. Good luck!
 

Raigar

Member
Dec 27, 2017
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5
0
S20+ AT&T

Hi Varcor,

I'm new in this firmware things. I'm from Singapore and has been using S20 Exynos, but due to the extreme heat, bad battery life,etc. I've decided to import S20+ Snapdragon from AT&T, according to the Service provider SW ver information, it's showing as SAOMC_SM-G986U-OYN_ATT_QQ_0023 (I believe this means the set are unlocked).

With that said, I noticed that the software is outdated and the security patch level is on February 1,2020. when I referring to the AT&T website, It's showing as the latest software is QP1A.190711.020.G986USQU1ATE6 (June update) and mine still on QP1A.190711.020..G986USQU1ATAW (February). My CSC is G986UOYN1ATAW.

My question now is, whenever I tried to hit the software update, it's keep telling me that my software is up to date. Is there's a reason why it's wont detect the update? If it's because I'm in Singapore not US, then there's no choice that I need to flash using the firmware from Sammobile. The problem is which one that I need to download as AT&T carrier is not listed there. There's only T-mobile, Sprint, Unknown, USA. Please help.

https://www.sammobile.com/samsung/galaxy-s20-plus/firmware/#SM-G986U
 

varcor

Senior Member
Jul 15, 2017
335
86
28
San Diego
Hi Varcor,

I'm new in this firmware things. I'm from Singapore and has been using S20 Exynos, but due to the extreme heat, bad battery life,etc. I've decided to import S20+ Snapdragon from AT&T, according to the Service provider SW ver information, it's showing as SAOMC_SM-G986U-OYN_ATT_QQ_0023 (I believe this means the set are unlocked).

With that said, I noticed that the software is outdated and the security patch level is on February 1,2020. when I referring to the AT&T website, It's showing as the latest software is QP1A.190711.020SAOMC_SM-G986U-OYN_ATT_QQ_0023 (June update) and mine still on QP1A.190711.020..G986USQU1ATAW (February). My CSC is G986UOYN1ATAW.

My question now is, whenever I tried to hit the software update, it's keep telling me that my software is up to date. Is there's a reason why it's wont detect the update? If it's because I'm in Singapore not US, then there's no choice that I need to flash using the firmware from Sammobile. The problem is which one that I need to download as AT&T carrier is not listed there. There's only T-mobile, Sprint, Unknown, USA. Please help.

https://www.sammobile.com/samsung/galaxy-s20-plus/firmware/#SM-G986U
I would reach out to SamMobile and inquire why they're not listing the AT&T Firmware Update. You state your CSC is G986UOYN1ATAW. That CSC is also associated with T-Mobile. You're not using an AT&T SIM Card, correct? On a Multi-CSC Device when you insert a different SIM, the device should update to the correct Service Provider. If you're using a SIM from a Service Provider other than AT&T you probably won't receive AT&T Software Updates, which are distributed by Samsung, not AT&T via OTA.
 

Raigar

Member
Dec 27, 2017
29
5
0
I would reach out to SamMobile and inquire why they're not listing the AT&T Firmware Update. You state your CSC is G986UOYN1ATAW. That CSC is also associated with T-Mobile. You're not using an AT&T SIM Card, correct? On a Multi-CSC Device when you insert a different SIM, the device should update to the correct Service Provider. If you're using a SIM from a Service Provider other than AT&T you probably won't receive AT&T Software Updates, which are distributed by Samsung, not AT&T via OTA.
I did try to reach them, but for some reason they are giving me some irrelevant answer. Something like "You probably don't get OTA-updates (otherwise you got them already from AT&T)". We are having a conversation breakdown there, I think they are not an english speaker (or my english is just bad). Really? that CSC is associated with T-Mobile? now I'm getting more confused because the box is stated AT&T and it's sealed.

I'm using Singapore SIM card (Singtel), so you were saying this set I'm using right now is a Multi-CSC device? If i were to flash to the other carrier firmware, will it create any problem?
 

varcor

Senior Member
Jul 15, 2017
335
86
28
San Diego
I did try to reach them, but for some reason they are giving me some irrelevant answer. Something like "You probably don't get OTA-updates (otherwise you got them already from AT&T)". We are having a conversation breakdown there, I think they are not an english speaker (or my english is just bad). Really? that CSC is associated with T-Mobile? now I'm getting more confused because the box is stated AT&T and it's sealed.

I'm using Singapore SIM card (Singtel), so you were saying this set I'm using right now is a Multi-CSC device? If i were to flash to the other carrier firmware, will it create any problem?
Flashing Singtel Firmware won't work since it's configured for the Exynos SoC. Multi-SIM Devices have only regional Service Providers available, you don't have Singtel as an option in an AT&T device. Based on your situation I would consider one of two options. The first would be insert an AT&T SIM just for OTA updates. Not sure if you received an AT&T SIM when you purchased the device, if you didn't they're not hard to find. The second and likely best option is sell the device and purchase a Global Variant with a Snapdragon SoC, you'll receive updates regardless of your Service Provider. If it makes you feel any better there's lots of users in the same predicament. They want the Snapdragon device in regions selling mainly Exynos devices. Workarounds are in many situations are challenging,
 
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itchyUnder

Member
Nov 14, 2010
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Your device has Multiple CSC's which are included in OYM so you should be able to change your CSC to ATT, which is the CSC for AT&T.

Go to "Settings" then "About phone". Write down your IMEI Number. Open dialer and enter *#272*IMEInumber# (In the thread replace IMEInumber with your actual IMEI Number). Press the Dial Icon, you should see a screen with the list of available CSC codes for your device. Select ATT and tap the Install option.

Be aware your firmware isn't AT&T, it's unbranded so even if you change the CSC, full call functionality may not be available. You can obtain AT&T's firmware at SamMobile.

https://www.sammobile.com/samsung/galaxy-s20-ultra/firmware/SM-G988U1/ATT/
Varcor

I have the exact same phone and using the same network as garyHal, unlocked 988U1/OYM/ATT.

I got my bootloader unlocked and decided to apply the ATT firmware (
G988U1UES1BTJ2). My CSC was already ATT so I didn't perform the csc install step.

After setting the phone up as new, it still seems like its running the unlocked mode. I don't see any kind of branding or extra ATT stuff that may have been downloaded. How do I verify that I have the right firmware and CSC set to ATT?

Thank you.
 

varcor

Senior Member
Jul 15, 2017
335
86
28
San Diego
Varcor

I have the exact same phone and using the same network as garyHal, unlocked 988U1/OYM/ATT.

I got my bootloader unlocked and decided to apply the ATT firmware (
G988U1UES1BTJ2). My CSC was already ATT so I didn't perform the csc install step.

After setting the phone up as new, it still seems like its running the unlocked mode. I don't see any kind of branding or extra ATT stuff that may have been downloaded. How do I verify that I have the right firmware and CSC set to ATT?

Thank you.
How did you manage to unlock your bootloader since US Snapdragon variants are locked down pretty tight? I don't think the firmware is dedicated to ATT, it's Multi CSC, designed to function with a number of US Carriers. You should be delighted you're not suffering with ATT bloatware! To check the Active CSC go to About Phone, Settings, Software Information, Service Provider SW ver. On the bottom string the first three letters are the Active CSC on your device. You can review this article for additional information on Firmware and CSC's.

 

itchyUnder

Member
Nov 14, 2010
48
4
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How did you manage to unlock your bootloader since US Snapdragon variants are locked down pretty tight? I don't think the firmware is dedicated to ATT, it's Multi CSC, designed to function with a number of US Carriers. You should be delighted you're not suffering with ATT bloatware! To check the Active CSC go to About Phone, Settings, Software Information, Service Provider SW ver. On the bottom string the first three letters are the Active CSC on your device. You can review this article for additional information on Firmware and CSC's.

If I am reading it correctly, this is what I am seeing:
ATT/ATT/XAA

I am happy that I don't have the ATT bloatware but I also feel that ATT is locking me out of some of their features because I don't have a "branded" phone, such as wifi call or visual voicemail. Am I misunderstanding your post from above, #6, that flashing ATT firmware would give me the carrier features?

Additionally, does the firmware determine what frequency bands I am using and if I am taking full advantage of ATT's offerings?
 
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varcor

Senior Member
Jul 15, 2017
335
86
28
San Diego
If I am reading it correctly, this is what I am seeing:
ATT/ATT/XAA

I am happy that I don't have the ATT bloatware but I also feel that ATT is locking me out of some of their features because I don't have a "branded" phone, such as wifi call or visual voicemail. Am I misunderstanding your post from above, #6, that flashing ATT firmware would give me the carrier features?

Additionally, does the firmware determine what frequency bands I am using and if I am taking full advantage of ATT's offerings?
Flashing ATT Dedicated Firmware would give you the best chance for additional call features ASSUMING your Ulocked Device is capable of incorporating those features. It should do the trick since the hardware is identical to an ATT device. I would head to an ATT Store to get a definitive answer. Samsung has made it more and more challenging to mix and match branded and unlocked devices with CSC or Firmware modifications. In many cases you won't know until you try. Users want their smartphones to be smart, to work perfectly in every situation but the major carriers use proprietary tools to hold clients hostage.